Lactarius torminosus
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Lactarius torminosus, commonly known as the woolly milkcap or the bearded milkcap, is a large basidiomycete fungus in the genus Lactarius. It is a common and widely distributed fungus, found in North Africa, northern Asia, Northern Europe, and North America. A mycorrhizal species, L. torminosus associates with various trees, most commonly birch, and its fruit bodies (mushrooms) grow on the ground singly or in groups in mixed forests. Although it is valued for its peppery flavor and eaten after suitable preparation in Russia and Finland, it is highly irritating to the digestive system when eaten raw. The toxins responsible for the acrid taste are destroyed by cooking. Studies have identified several chemicals present in the mushrooms, including ergosterol and derivatives thereof, and the pungent-tasting velleral, a compound thought to be responsible for the toxicity of the raw mushroom.
The caps of L. torminosus mushrooms are convex with a central depression, and attain a diameter of up to 10 cm (3.9 in). Its color is a blend of pink and ochre hues, sometimes with concentric zones of darker shades. The edge of the cap is rolled inwards, and shaggy when young. On the underside of the caps are narrow flesh-colored gills crowded closely together. It is on these fertile gill surfaces that the spore-bearing cells, the basidia are found. The cylindrical stem is a pale flesh color with a delicately downy surface, reaching a length of up to 8 cm (3.1 in) and a thickness of 0.6–2 cm (0.2–0.8 in). When cut or injured, the fruit bodies ooze a white latex that does not change color upon exposure to air. The variety normandensis, in contrast, has latex that changes from white to yellow.
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[edit] Taxonomy, classification, and phylogeny
The species was originally described scientifically by the German naturalist Jacob Christian Schäffer in 1774; he named it Agaricus torminosus.[2] Seven years later in 1781, Jean Bulliard named a species Agaricus necator and illustrated it in the first volume of his Herbier de la France.[3] This name, and its later name Lactarius necator (transferred to Lactarius in 1800 by Christian Hendrik Persoon[4]), are now considered synonymous with L. torminosus.[5] According to Index Fungorum,[1] additional older synonyms include Lactarius necans (Gray, 1821),[6] Galorrheus torminosus (Kummer, 1871),[7] and Lactifluus torminosus (Kuntze, 1891).[8]
The specific epithet torminosus means "tormenting" or "causing colic", referring to the gastrointestinal distress associated with consuming the mushroom.[9] Early English vernacular names were Gray's "bellyach milk-stool" (1821),[6] and James Edward Smith's "bearded pepper agaric" (1824).[10] More recent common names include the "shaggy milkcap",[11] the "powderpuff milkcap",[12] the "pink-fringed milkcap",[13] , the "bearded milkcap",[14] and the British Mycological Society-recommended "woolly milkcap".[15]
Lactarius torminosus is classified in the subgenus Piperites, section Piperites (in which it is the type species), subsection Piperites of the genus Lactarius. Species in this subsection are characterized by having latex that does not turn yellow after exposure to air, and/or that does not stain the cut surface of the mushroom surface yellow.[16] A 2004 phylogenetic analysis of European Lactarius species concluded that L. torminosus falls into a well-supported clade that includes L. torminosulus, and that these two species are sister to a clade that includes L. tesquorum, L. scoticus, and L. pubescens.[17]
[edit] Description
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The cap is initially convex, but as it matures, the center of the cap forms a depression, and the outer edges become raised until it eventually assumes the shape of a shallow funnel; its width is typically between 2 and 12 cm (0.8 and 4.7 in). The cap margin is curled strongly inwards, and when young is tomentose (covered with a thick matting of hairs) that forms an apparent veil that partly covers up the gills. In age, the dense tomentum withers to sparse whitish fibers. Similarly, the cap surface is initially tomentose, but eventually the hairs wear off, leaving the surface more of less smooth.[18] The surface is initially somewhat sticky on the central portion, bearing concentric zones of darker shades that usually fade in maturity, especially near the edge of the cap.[12] The overall cap color is pinkish-orange to pale dull pink, becoming orange to whitish on the margin, with the pink gradually fading. The white to flesh-colored flesh is firm and brittle, but becomes flaccid in age. The latex that is produced when the mushroom tissue in cut or injured is white to cream, and does not change color with prolonged exposure to air, nor does it stain the gills. It has an acrid taste, with a slight to pungent odor.[18]
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The gills are subdecurrent (running a little ways down the length of the stem), close to crowded together, narrow, and are sometimes forked near the stem. Their color is whitish, becoming pale vinaceous (the color of red wine) to pale orange or cream tinged vinaceous, turning pale tan with age. The stem is 1.5–8 cm (0.6–3.1 in) long, 0.6–2 cm (0.2–0.8 in) thick, fragile, more or less equal in width throughout, cylindrical or narrowed at the base. The surface of the stem is dry, and either smooth to pruinose (covered with a very fine whitish powder on the surface). Its color is pale light pinkish to yellowish tinged or slightly pinkish orange to orange white, sometimes spotted. The flesh of the stem is firm, beige white, and stuffed (as if filled with cotton), but it eventually becomes hollow.[18] Occasionally, white mycelium is present at the base of the stem.[19]
[edit] Microscopic characteristics
The spore print of L. torminosus is cream to pale yellow. The spores are 8–10.2 by 5.8–6.6 μm, roughly spherical to broadly elliptical in side view, and hyaline (translucent). The ornamentation on the surface of the spores is amyloid, partially reticulate (network-like) with interrupted ridges roughly 0.5–0.7 μm high, and a few isolated warts. The spore has a conspicuous apiculus, demarcating where it was once attached to the basidia via the sterigma. The basidia are four-spored, club-shaped to cylindrical, and hyaline, measuring 30–47.7 by 7.3–8.2 μm. Pleurocystidia are only present in the form of macrocystidia (very long cystidia) embedded and originating in the hymenium and just below it, measuring 40.3–80.0 by 5.1–9.5 μm. Macrocystidia are abundant in the hymenium, and are characterized by their spindle-shaped to ventricose (swollen on one side) form that gradually tapers in width, with granular hyaline contents. The cheilocystidia are 30–52 by 4.5–8.0 μm, also in the form of macrocystidia. The cap cuticle is an ixocutis (made of gelatinized interwoven hyphae arranged more or less parallel to the cap surface); the thin-walled, threadlike hyphae of this layer are 2.5–7.3 μm wide.[18]
[edit] Development
The fruit body formation of L. torminosus is pileostipitocarpic (sometimes termed pseudoangiocarpic). In this type of development, the hymenium forms early on the underside of the cap and upper stem of the mushroom primordium. As the cap enlarges, the margin, made of flaring filamentous hyphae that grow outward and downward, tends to curve inward, eventually forming a flap of tissue situated roughly parallel to the stem surface. As further development takes place, these hyphae make contact with and adhere to the hymenial surface of the stem, covering basidia and macrocystidia already present. The junction between the two tissues produces a cavity that provides some temporary protection to the basidia, although they are already fertile when the cap margin starts to grow.[20]
[edit] Variety normandensis
Lactarius normandensis was described by Alexander H. Smith in 1960 to account for the North American species closely resembling L. torminosus, but having instead latex that changed color from white to yellow upon exposure, and that stained tissues and paper yellow.[21] Hesler and Smith reduced this taxon to the status of variety in 1979.[22] Lactarius torminosus var. normandensis has been collected from California,[23] Idaho, Michigan and Wisconsin in the United States, from Quebec in Canada, and from Switzerland. The variety resembles Lactarius pubescens var. betulae, but differs in its longer pleurocystidia, larger spores with slightly different spore ornamentation, and its strongly burning acrid taste.[22] The holotype specimen, collected by Smith near Nordman, Idaho in 1956, is kept in the fungus collection at the University of Michigan Herbarium.[24]
[edit] Similar species
Lactarius torminosulus is a dwarf version of L. torminosus, an arctic species associated with the birch species Betula nana or B. glandulosa.[25] Immature fruit bodies of L. scrobiculatus resemble L. torminosus, but they have a white latex that soon changes yellow upon exposure to air, and their stems have depressed shiny spots. The caps of the poorly known species L. cilicioides are zoned, and its spores are smaller. L. pubescens is physically quite similar, but can be distinguished by its paler color and smaller spores (6.0–7.5 by 5.0–6.5 μm).[18] L. controversus has a cap margin that is not as hairy, whitish to cream-colored gills, and larger spores measuring 7.5–10 by 6–7.5 μm.[26] L. mairei has a coloration similar to L. torminosus, but is rarer and typically found associated with oak trees on calcareous soil.[27] The similar North American species L. villosus is white before becoming tinted with orange, and has smaller spores.[12] L. subtorminosus, known only from North Carolina and western Canada,[28] was named for its similarity to L. torminosus. It can be distinguished by its mild-tasting latex,[29] and smaller, roughly spherical spores measuring 5.5–7 by 5.5–6.5 μm.[30]
[edit] Edibility and toxicity
The intensely peppery taste of the raw mushroom can blister the tongue if sampled in sufficient quantity.[13] Some authors have reported the species as poisonous,[9][31] or causing "mild to fatal gastroenteritis".[32] In a 1930 publication, Hans Steidle reported that although the mushroom was not toxic to "unicellular and cold-blooded organisms", the liquid extract and the pressed juice of the fruit bodies, when injected under the skin of a frog, resulted in disturbed breathing, paralysis, and eventually death.[33] Symptoms that are typically experienced after consuming raw mushrooms include nausea, vomiting, and severe diarrhea that starts about one hour after ingestion. This combination can lead to dehydration, muscle spasms, and circulatory collapse. Poisonings are, however, quite rare, and the gastroenteritis will usually resolve without treatment in a couple of days.[34]
Despite the reports of toxicity, in Finland, Russia, and other northern and eastern European countries, L. torminosus mushrooms are prepared by parboiling, soaking in brine for several days, or pickling, after which it is valued for its peppery taste. In Norway it is roasted, and added to coffee.[14][27] Mushrooms are harvested for commercial sale in Finland.[12] The nutritional composition of Finnish specimens has been analyzed and found to contain the following components (as a percentage of dry weight): protein, 17.2%; phosphorus, 0.46%; calcium, 0.12%; magnesium, 0.088%; potassium, 2.97%; sodium 0.011%.[35]
[edit] Ecology, distribution, and habitat
Lactarius torminosus is a mycorrhizal species, and it plays an important role in facilitating nutrient and water uptake by trees. It grows in association with birch (Betula) and hemlock (Tsuga) in mixed forests. It is also known to grow in urban settings where birch trees are nearby.[18] A field study conducted in Scotland determined that the species is more likely to be found in older rather than younger birch woodlands.[36] Fruit bodies grow on the ground, scattered to grouped together. The species is found in North Africa, northern Asia,[27] United Kingdom, Northern Europe, and is common in North America, where it sometimes grows with aspen (Populus species).[14] The North American distribution extends north into the Yukon and Alaska,[37] and south to Mexico.[38]
The fruit bodies are a component of the diet of the red squirrel Sciurus vulgaris,[35] and serve as breeding sites for fungus-feeding flies in the Drosophilidae and Mycetophilidae families.[39] Lactarius torminosus mushrooms may be parasitized by the mold Hypomyces lithuanicus, which produces a cream-ochre to cinnamon-colored granular or velvety growth of mycelium on the surfaces of the gills and causes them to be deformed.[40]
[edit] Bioactive compounds
Lactarius torminosus contains the lactarane-type sesquiterpene lactone 15-hydroxyblennin A. This sesquiterpenoid has a lactarane skeleton, similar to compounds found in other Lactarius species, such as Lactarius deliciosus, Lactarius blennius (blennin A), and Lactarius rufus (lactarorufin N, deoxydihydroketolactarorufin N).[41] Fruit bodies contain a number of sterols, of which ergosterol is the predominant component at 60.5% (of total sterols), followed by the ergosterol derivatives ergost-7-en-3-ol (13.7%), ergosta-7-22-dien-3-ol (8.3%), and ergosta-5/7-dien-3-ol (17.0%).[42] The mushrooms also contain the compound velleral, a breakdown product of stearyl-velutinal, which is contained within the lactifers—specialized hyphal cells that produced the mushroom's latex. It has been suggested that broken lactifers leak precursors whose breakdown products act as defensive agents toxic to humans and effectively deter certain vertebrates that might consume the mushroom. Velleral, which has an extremely pungent taste and is thought to be responsible for the toxicity of the raw mushroom, is present at a concentration of 0.16 mg/g mushroom.[43]
[edit] See also
[edit] References
- ^ a b "Species synonymy: Lactarius torminosus (Schaeff.) Gray". Index Fungorum. CAB International. http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=228133. Retrieved 2012-03-14.
- ^ Schäffer JC. (1774) (in Latin and German). Fungorum qui in Bavaria et Palatinatu Nascuntur Icones. 4. Erlangen, Germany: Erlangae, Apud J.J. Palmium. p. 7. http://www.archive.org/stream/fungorumquiinbav34schf#page/6/mode/2up.
- ^ Bulliard JBF. (1781). Herbier de la France [Guide to the Herbs of France]. 1. pp. 1–48, plate 28. http://www.archive.org/stream/herbierdelafranc148bull#page/28/mode/2up.
- ^ Persoon Christian Hendrik (1799) (in Latin). Observationes mycologicae seu Descriptiones tam novorum, quam notabilium fungorum. Leipzig, Germany: Gesnerus, Usterius & Wolfius. p. 42.
- ^ "Lactarius necator (Bull.) Pers. 1800". MycoBank. International Mycological Association. http://www.mycobank.org/MycoTaxo.aspx?Link=T&Rec=355713. Retrieved 2010-07-13.
- ^ a b Gray SF. (1821). A Natural Arrangement of British Plants. London, UK: Baldwin, Cradock, and Joy. p. 623. http://books.google.com/books?id=g-EYAAAAYAAJ&pg=PA623.
- ^ Kummer P. (1871) (in German). Der Führer in die Pilzkunde. Zerbst, Germany: E. Luppe Staude. p. 125. http://biodiversitylibrary.org/page/34209694.
- ^ Kuntze O. (1898) (in Latin). Revisio Generum Plantarum. 3. Leipzig, Germany: Arthur Felix. p. 857.
- ^ a b Roody WC. (2003). Mushrooms of West Virginia and the Central Appalachians. Lexington, Kentucky: University Press of Kentucky. p. 107. ISBN 0813190398. http://books.google.com/books?id=5HGMPEiy4ykC&pg=PA107.
- ^ Smith JE. (1824). The English flora. 5. London, UK: Longman, Hurst, Rees, Orme, Brown, and Green. p. 24. http://biodiversitylibrary.org/page/6100576.
- ^ Dickinson C, Lucas J. (1982). VNR Color Dictionary of Mushrooms. New York, New York: Van Nostrand Reinhold. p. 104. ISBN 9780442219987.
- ^ a b c d McKnight VB, McKnight KH. (1987). A Field Guide to Mushrooms: North America. Peterson Field Guides. Boston, Massachusetts: Houghton Mifflin. p. 337. ISBN 0395910900.
- ^ a b Arora D. (1991). All that the Rain Promises and More: A Hip Pocket Guide to Western Mushrooms. Berkeley, California: Ten Speed Press. p. 19. ISBN 0898153883. http://books.google.com/books?id=87ct90d4B9gC&pg=PA19.
- ^ a b c Arora D. (1986). Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi. Berkeley, California: Ten Speed Press. p. 73. ISBN 0898151694. http://books.google.com/books?id=L-4ajFDPlxgC&pg=PA73.
- ^ "List of recommended English Names for Fungi in the UK" (PDF). British Mycological Society. 2003. http://www.fungi4schools.org/Reprints/ENGLISH_NAMES.pdf.
- ^ Hesler and Smith (1979), p. 237.
- ^ Nuytinck J, Verbeken A, Rinaldi AC, Leonardi M, Pacioni G, Comandini O. (2004). "Characterization of Lactarius tesquorum ectomycorrhizae on Cistus sp. and molecular phylogeny of related European Lactarius taxa". Mycologia 96 (2): 272–82. JSTOR 3762063. PMID 21148854. http://www.cybertruffle.org.uk/cyberliber/59350/0096/002/0272.htm.
- ^ a b c d e f Ammirati JF, Traquair JA, Horgen PA. (1985). Poisonous Mushrooms of Canada: Including other Inedible Fungi. Markham, Ontario: Fitzhenry & Whiteside in cooperation with Agriculture Canada and the Canadian Government Publishing Centre, Supply and Services Canada. pp. 275–6. ISBN 0889029776.
- ^ Bessette et al. (2009), pp. 257–8.
- ^ Watling R. (1985). "Hymenial surfaces in development agaric primordia". Botanical Journal of the Linnean Society 91 (1–2): 273–93. doi:10.1111/j.1095-8339.1985.tb01150.x.
- ^ Smith AH. (1960). "Studies of Lactarius – II. The N.A. species of sections Scrobiculus, Crocei, Theiogali and Vellus". Brittonia 12 (4): 306–50. JSTOR 2805123.
- ^ a b Hesler and Smith (1979), pp. 277–8.
- ^ Methven AS. (1985). "New and interesting species of Lactarius from California". Mycologia 77 (3): 472–82. JSTOR 3793204. http://www.cybertruffle.org.uk/cyberliber/59350/0077/003/0472.htm.
- ^ "Lactarius nordmanensis; Russulaceae (MICH5267)". Herbarium Fungus Collection Database. University of Michigan. http://quod.lib.umich.edu/cgi/i/image/image-idx?id=S-HERB5IC-X-MICH5267%5DMICH5267.TIF. Retrieved 2010-07-13.
- ^ Knudsen H, Borgen T. (1994). "The Lactarius torminosus-group in Greenland". Mycologia Helvetica 2: 49–56.
- ^ Evenson VS. (1997). Mushrooms of Colorado and the Southern Rocky Mountains. Englewood, Colorado: Westcliffe Publishers. p. 77. ISBN 9781565791923. http://books.google.com/books?id=EAeDeyqZLq0C&pg=PA77.
- ^ a b c Roberts P, Evans S. (2011). The Book of Fungi. Chicago, Illinois: University of Chicago Press. p. 193. ISBN 9780226721170.
- ^ Bessette et al. (2009) p. 249.
- ^ Coker WC. (1918). "Lactarias of North Carolina". Journal of the Elisha Mitchell Scientific Society 34 (1–2): 1–62 (see p. 18). http://www.biodiversitylibrary.org/page/9560048.
- ^ Hesler and Smith (1979), p. 227.
- ^ Redhead S, Groves JW. (1979). Edible and Poisonous Mushrooms of Canada. Ottawa, Canada: Research Branch, Agriculture Canada. ISBN 066010136X.
- ^ Elvin-Lewis MPF, Lewis WH. (2003). Medical Botany: Plants Affecting Human Health. Chichester, UK: John Wiley & Sons. p. 61. ISBN 0471628824. http://books.google.com/books?id=ipQmSriMF9sC&pg=PA61.
- ^ Steidle H. (1930). "Contributions to the toxicology of the higher mushrooms. 1st note: Lactarius torminosus". Archiv für Experimentalle Pathologie und Pharmakologie 151 (3/4): 232–54.
- ^ Reichl F-X, Ritter L. (2011). Illustrated Handbook of Toxicology. Stuttgart, Germany: Thieme. p. 296. ISBN 9783131495914. http://books.google.com/books?id=9hHACrSGgyIC&pg=PT296.
- ^ a b Grönwall O, Pehrson Å. (1984). "Nutrient contents in fungi as a primary food of the red squirrel Sciurus vulgaris L.". Oecologia (Berlin) 64 (2): 230–1. doi:10.1007/BF00376875. JSTOR 4217450.
- ^ Watling R. (1981). "Relationships between macromycetes and the development of higher plant communities". In Wicklow DT, Carroll GC. The Fungal Community: Its Organization and Role in the Ecosystem. New York, New York: Marcel Dekker. pp. 427–58. ISBN 9780824769567.
- ^ Schalkwijk-Barendsen HME. (1991). Mushrooms of Western Canada. Edmonton, Canada: Lone Pine Publishing. p. 215. ISBN 0919433472.
- ^ Guzmán G. (1973). "Some distributional relationships between Mexican and United States mycofloras". Mycologia 65 (6): 1319–30. JSTOR 3758146. PMID 4773309. http://www.cybertruffle.org.uk/cyberliber/59350/0065/006/1319.htm.
- ^ Shorrocks B, Charlesworth P. (1980). "The distribution and abundance of the British fungal-breeding Drosophila". Ecological Entomology 5 (1): 61–78. doi:10.1111/j.1365-2311.1980.tb01124.x.
- ^ Rogerson CT, Samuels GJ. (1994). "Agaricolous species of Hypomyces". Mycologia 86 (6): 839–66. doi:10.2307/3760597. JSTOR 3760597. http://www.cybertruffle.org.uk/cyberliber/59350/0086/006/0839.htm.
- ^ Widen KG, Seppa EL. (1979). "15-Hydroxyblennin A, a new lactarane-type sesquiterpene lactone isolated from Lactarius torminosus". Phytochemistry 18 (7): 1226–7. doi:10.1016/0031-9422(79)80144-2.
- ^ Cerri R, de Simone F, Senatore F. (1981). "Sterols from three Lactarius species". Biochemical Systematics and Ecology 9 (4): 247–8. doi:10.1016/0305-1978(81)90002-8.
- ^ Camazine S, Lupo TL Jr. (1984). "Labile toxic compounds of the Lactarii: the role of the laticiferous hyphae as a storage depot for precursors of pungent dialdehydes". Mycologia 76 (2): 355–8. JSTOR 3793113. http://www.cybertruffle.org.uk/cyberliber/59350/0076/002/0355.htm.
[edit] Cited texts
- Bessette AR, Bessette AE, Harris DB. (2009). Milk Mushrooms of North America: A Field Guide to the Genus Lactarius. Syracuse, New York: Syracuse University Press. ISBN 0815632290.
- Hesler LR, Smith AH. (1979). North American Species of Lactarius. Ann Arbor, Michigan: The University of Michigan Press. ISBN 0472084402.
[edit] External links
